The present invention is directed to control devices for bicycle transmissions and, more particularly, to a bicycle shift control device for controlling a gas actuated shifting device.
U.S. Pat. No. 6,066,057 entitled "Gas Actuated Transmission for a Bicycle" discloses various embodiments of a gas actuated shifting device for bicycles wherein air controlled shift valves in the form of toggle switches are used to selectively upshift and downshift a gas actuated transmission. Such shift valves can be placed in various positions on the bicycle. However, if the shift valves are formed as separate units, then it may be difficult to position the shift valves in an ergonomic manner.
Some shift control devices use two levers in close proximity to each other for respectively upshifting and downshifting the bicycle transmission. Such a device is disclosed in U.S. Pat. No. 5,564,310, for example. The shifting device disclosed in that patent includes two levers that operate in opposite directions to respectively upshift and downshift a bicycle transmission. Such a shifting device is very convenient, but such convenience so far has not been realized in a shift control device for controlling a gas actuated bicycle transmission.